Major Traits Breeding Potentiality Analysis Of Five Synthesized Corn Populations

Development is mainly restricted by lack of germplasm resources in China in maize breeding. In order to change this situation, maize breeders have done considerable researches. This experiment was made with 5 synthesized corn populations and 45 combinations derived form crosses to 9 testers based on an incomplete diallel disign. These materials were provided by SiChuan Agricultural University Corn Research Institute and SiChuan Academy of Agricultural sciences. The incomplete diallel crosses were used to study the major agronomic traits, heterotic groups and combing ability. The main results were summarized as follows:1. Variance was significant in all the observed traits except for pollen shedding phase, silk phase, green leaf duration, kernel /row, seeding rate and kernel depth in the 5 populations (chart 1).2. Comparisons of main means(chart 2) showed that plant height and ear height were higher in GP-1 and GP-2; kernels/row , ear weight, grain yield and yield per plant were higher in GP-3 and GP-5, and plant height and ear height were lower in GP-4; From the comparisons of main agronomic economical traits CV(chart 2), great genetic variation was detected within the 5 synthesized corn populations while the extent of genetic variation was different. Comparatively, greater genetic variation was detected in plant height and ear height in GP-4, ear length in GP-1, kernels/row, ear weight, grain yield and yield per plant in GP-2,100-kernel weight in GP-5. There was lower genetic variation in GP-3.3. Normal distribution was observed in yield per plant in five population. The average yield per plant of checked variety (160g) was used as a standard. The frequency of average yield per plant higher than 160g in each population was different. Results showed the frequencies of GP-1, GP-2, GP-3, GP-4, GP-5 were 28%, 26%, 31%, 14%, 26%, respectively.4. Analysis of combing ability in traits with significant variations in the two seasons showed that GP-5 and GP-3 were higher in GCA in the major agronomic economical traits, while only one prominent trait was detected in the other 3 populations, (chart 5 and chart 6). There was a significant variance in numbers of hybrids with significant SCA effect.Hybrid 698-3 xGP-1 showed maximum positive SCA effect twice. Hybrid 698-3 xGP-5 showed maximum negative SCA effect twice. GP-1 was used as a parent for hybrids with maximum positive and negative SCA effect in era length. GP-2 and GP-5 were used as parents for hybrids with maximum positive and negative SCA effect in the other three traits.5. The genetic distances (GD) of 5 synthesized corn populations were calculated based on data of 8 agronomic economical traits, 5 synthesized corn populations were classified into 3 groups, group I including GP-1 and GP-2, group II including GP-3 and GP-5,group III including GP-4. comparisons of SCA in plant yield in the 20 hybrid combinations with model tester were used as a basis for the classification of heterotic groups(chart 7). The 5 synthesized corn populations were classified into four heterotic groups. The four groups were GP-3 and Huang zaosi, GP-5 and Mo 17, GP-4 and Ye478, GP-1 ? GP-2 and Dan340 or Ye478, respectively. Among the 11 hybrid combinations with positive effect over the check yield per plant(chart 8), when ES40, R08 and 48-2 were used as one parent, the possibility of getting hybrids with higher yield per plant in GP-5 was great. GP-4 and GP-3 followed the order. About the heterotic groups of ES40, R08 and 48-2, further research was necessary.It concluded that GP-3 and GP-5 are appropriate in plant height and ear height, with higher traits means, better general combining ability, greater frequencies of elite individuals, and higher coenobium frequency compared with the check variety. They were proved to have a better breeding potentiality. GP-4 is lower in means of major yield traits, with a positive GCA, a lower plant height and ear height, and a higher coenobium frequency compared with check variety. It may also have potentiality for exploitation in breeding through improvement of GCA and SCA selection. GP-1 and GP-2 showed higher plant height and ear height, with a negative GCA in major traits and a lower coenobium frequency compared with the check variety, so they seemed to have less breeding potentiality.